In recent motorcycles, a throttle position sensor such as a potentiometer detects a rotation angle of a throttle grip and transmits an electric signal representing the detection value to an electric control device and the like mounted on the motorcycle. The electric control device performs calculation based on the detection signal and controls an ignition timing of the engine and opening or closing of an air intake valve or a throttle valve based on the calculation result.
For example, JP-A-2015-81564 discloses a throttle grip apparatus which has a constant-speed maintaining device (a cruise control device) for maintaining a constant running speed and controls an engine of a vehicle according to a rotation angle of a throttle grip if the throttle grip is rotated in a normal direction which is a predetermined direction, and stops (cancels) speed maintaining control of the constant-speed maintaining device if the throttle grip is rotated in the opposite direction to the predetermined direction.
The throttle grip apparatus includes an interlocking member configured to rotate in conjunction with the throttle grip when the throttle grip is rotated in the normal direction which is the predetermined direction, a sliding member configured to slide in conjunction with the throttle grip when the throttle grip is rotated in the opposite direction to the predetermined direction, a first biasing unit configured to bias the interlocking member toward its initial position, and a second biasing unit configured to bias the sliding member toward its initial position, and the sliding member and the second biasing unit are installed inside the interlocking member.
In the throttle grip apparatus, since the throttle grip has only one engaging part to be engaged with the interlocking member, and the second biasing unit also has only one engaging part to be engaged with the interlocking member, when the throttle grip is rotated or when the throttle grip returns to the initial position by the biasing force of the second biasing unit, the rotation becomes unstable so that the operability deteriorates. Further, in the above throttle grip apparatus, since only one second biasing unit is installed inside the interlocking member with respect to the rotation direction of the throttle grip, a spring or the like having a relatively large biasing force should be used as the second biasing unit.
Also, the throttle grip apparatus includes a rotation angle detecting unit having a magnet installed inside the interlocking member and a magnetic sensor configured to detect a change in the magnetic force from the magnet, and detects the rotation angle of the throttle grip by the rotation angle detecting unit. However, since the magnet and the second biasing unit need to be installed inside the interlocking member, the size of the interlocking member increases, and the installation position of the magnetic sensor is limited. Therefore, flexibility in the layout of the inside of the apparatus decreases.
In order to solve those problems, it can be considered to provide a rotary member capable of rotating in conjunction with the interlocking member and detect the rotation angle of the rotary member by the rotation angle detecting unit, thereby detecting the rotation angle of the throttle grip, and install the magnet outside the interlocking member. However, in this case, besides the interlocking member for accommodating the second biasing member, it is necessary to provide a transmission unit for transmitting rotation of the interlocking member to the rotary member to rotate. In this case, since a space for installing the rotary member and a space for the transmission unit are required separately, the size of the whole of the apparatus increases.